Bucket loaders are an optional attachment that can be mounted on tractors to provide material handling capability. The bucket loader typically has a frame that is detachably supported on the tractor, a pair of forwardly extending boom arms pivotally mounted on the frame, and a bucket pivotally supported on the forward ends of the boom arms to engage material forwardly of the tractor. The bucket is typically pivotable to scoop material, moving the front edge of the bucket up and down, while the pivotally movable boom arms are operable to raise and lower the bucket.
The tractor providing motive and operational power for the bucket loader can be substantially any size from the large farm tractors to the small garden tractors that are often used to mow lawns in a residential setting. Large tractors have onboard hydraulic systems that are used to power hydraulic cylinders mounted on the bucket loader to cause pivotal movement of the components thereof. The smaller garden tractors do not typically carry onboard hydraulic systems, requiring any actuators powering the pivotally movable components of the bucket loader to be electrical, rather than hydraulic. All terrain vehicles (ATV), sometimes referred to as four-wheelers, can also have small bucket loaders mounted on them to increase the versatility and flexibility of operation thereof. Each operable function of the bucket loader conventionally requires a separate actuator. The boom lift function, particularly on large tractors, is powered by a pair of hydraulic cylinders, one positioned on each boom arm. The pivotal movement of the bucket relative to the boom arms is normally powered by a separate actuator.
Bucket loaders for small garden tractors and ATV's are usually constructed somewhat differently than the bucket loaders for large tractors. First, the overall size of the bucket loader apparatus is substantially smaller, as the bucket, boom arms and frame are sized to be adapted to the smaller garden tractor configuration. Since the bucket is relatively small and has a relatively small load capacity, the tilt function for the bucket can be operated and powered manually, reserving the actuator power for lifting the boom arms and the attached bucket. The pivotal range of such buckets, however, is limited, often resulting in the retention of some of the material loaded into the bucket when the bucket is tipped to empty the material from the bucket.
Split bucket configurations, often referred to as clamshell buckets, are known for larger bucket loader configurations, but are not particularly adaptable to the small bucket loaders because of the need to power the operation of the pivoted forward shell portion of the bucket relative to the rearward back plate portion on which the shell portion is pivotally mounted. The clamshell bucket has the extra advantage of being capable of opening the forward shell portion of the bucket to expose the back plate portion and enable the back plate portion to be operated as a blade to push material around, rather than lift the material in the bucket function.
It would be desirable to provide a bucket loader that would provide a clamshell bucket configuration for use on a small tractor or other vehicle. It would also be desirable to provide a linkage mechanism that would enable a single actuator to perform multiple functions on the bucket loader, particularly the functions of lifting the bucket and operating the clamshell bucket apparatus.